The small wing Darth Vader TIE Fighter is often thought of as the holy grail of die cast collecting with fewer than 50 prototype ships known to exist. The small wing version is identical to the production Darth Vader TIE apart from the significantly smaller wings. These wings being out of scale with the rest of the ship were subsequently redesigned prior to the TIE going to retail.
Carded examples of the small wing Darth Vader TIE can be found on two different mock-up cards. The first packaging tests can be found on a SW12 TIE card, with later production-like tests found on an unproduced Darth Vader TIE 20 back - not to be confused with the Canadian production version. The unproduced 20 back demonstrates that the ship was clearly close to production before Kenner decided to redesign it with larger wings.
The small wing Darth Vader TIE unproduced 20 back differs from the larger winged TIE's 21 back in a few subtle ways. Firstly the sample bubble and backing area was significantly smaller than that used for the production ship and as such there was more room on the card front. This led to more room above the bubble and resulted in a lower placed die cast starburst, and more of the film accurate TIE visible on the card art. Also absent on the sample TIE is the inner tray keeping Darth firmly in the driving seat - with disastrous consequences!
Small wing Darth Vader TIE on the right, with large wing TIE on the left for comparison.
The obvious main difference on the back is the lack of Boba Fett on the the 20 back, the action figure being released at the same time as the regular die cast Darth Vader TIE.